Re: [PATCH v4 1/4] Produce system time from correlated clocksource

From	Richard Cochran <richardcochran@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 1/4] Produce system time from correlated clocksource
Date	2015-10-20 11:00 +0200
Message-ID	<qlAVY-77N-11@gated-at.bofh.it> (permalink)
References	(2 earlier) <qjdKb-80D-49@gated-at.bofh.it> <qjFZL-8q-7@gated-at.bofh.it> <qjLVw-DS-5@gated-at.bofh.it> <qlsOK-3LO-9@gated-at.bofh.it> <qlt85-48v-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, Oct 19, 2015 at 05:36:56PM -0700, John Stultz wrote:
> If we're only tracking 4ms of history, how does this solution
> measurably improve the error over using the timestamps to generate
> MONOTONIC_RAW clock deltas (which doesn't require keeping any history)
> and using getnstime_raw_and_real to take an anchor point to calculate
> the delta from?  Why is adding complexity necessary?

This idea is variant of what I suggested in another reply in this
thread.  To my understanding, there is no need at all to keep a
history arbitrarily 4 ms long.  Instead, the DSP driver (or whoever
else may need such a thing) can simply sample the system time at the
rate needed for that particular application.

Thanks,
Richard
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Thread

Re: [PATCH v4 1/4] Produce system time from correlated clocksource "Christopher Hall" <christopher.s.hall@intel.com> - 2015-10-20 02:20 +0200
  Re: [PATCH v4 1/4] Produce system time from correlated clocksource John Stultz <john.stultz@linaro.org> - 2015-10-20 02:40 +0200
    Re: [PATCH v4 1/4] Produce system time from correlated clocksource Richard Cochran <richardcochran@gmail.com> - 2015-10-20 11:00 +0200
      Re: [PATCH v4 1/4] Produce system time from correlated clocksource Thomas Gleixner <tglx@linutronix.de> - 2015-10-20 12:50 +0200
        Re: [PATCH v4 1/4] Produce system time from correlated clocksource Richard Cochran <richardcochran@gmail.com> - 2015-10-20 14:00 +0200
          Re: [PATCH v4 1/4] Produce system time from correlated clocksource Richard Cochran <richardcochran@gmail.com> - 2015-10-20 17:00 +0200
            Re: [PATCH v4 1/4] Produce system time from correlated clocksource Thomas Gleixner <tglx@linutronix.de> - 2015-10-20 21:20 +0200
              Re: [PATCH v4 1/4] Produce system time from correlated clocksource Richard Cochran <richardcochran@gmail.com> - 2015-10-20 21:40 +0200
              Re: [PATCH v4 1/4] Produce system time from correlated clocksource John Stultz <john.stultz@linaro.org> - 2015-10-20 22:20 +0200
                Re: [PATCH v4 1/4] Produce system time from correlated clocksource Thomas Gleixner <tglx@linutronix.de> - 2015-10-21 09:50 +0200

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